Method and article from laminating non-foamed polyurethane elastomer to vinyl polymer with a fusion bond



Nov. 19, 1968 c. H. THOMAS 3,411,981

METHOD AND ARTICLE FROM LAMINATING NON'FOAMED POLYURETHANE ELASTOME-R TOVINYL POLYMER WITH A FUSION BOND Filed Feb. 24, 1966 2 Sheets-Sheet 1F5" 7.Z .i-i -5 INVENTOR Cyrus H .Thomos j yMuZVfl ATTORNEYS Nov. 19,1968 c. H. THOMAS 3,411,981

METHOD AND ARTICLE FROM LAMINATING NON'FOAMED POLYURETHANE ELASTOMER TOVINYL POLYMER WITH A FUSION BOND Filed Feb. 24, 1966 2 Sheets-Sheet 2INVENTOR Cyrus H. Thomas ATTORNEYS United States Patent 3,411,981 METHODAND ARTICLE FROM LAMINATING NON-FOAMED POLYURETHANE ELASTOMER TO VINYLPOLYMER WITH A FUSION BOND Cyrus H. Thomas, Miami, Fla., assignor toIndustrial Vinyls, Incorporated, a corporation of FloridaContinuation-impart of application Ser. No. 211,365, July 20, 1962. Thisapplication Feb. 24, 1966, Ser. No. 544,064

8 Claims. (Cl. 161190) ABSTRACT OF THE DISCLOSURE A resinous structurehaving a high bursting strength and abrasion resistance constructed froma laminate of a layer of a thermoplastic vinyl polymer and a thin layerof a thermoplastic polyurethane or a molded mixture of a thermoplasticvinyl polymer and a thermoplastic polyurethane.

This application is a continuation-in-part of my copending application,Ser. No. 211,365, filed July 20, 1962, and now abandoned.

This invention relates to novel, improved laminated plastic structuresand to methods for preparing same. In particular, the invention isconcerned with improved plastic structures comprising a thermoplasticpolyurethane resin.

Synthetic polymers may, in general, be classified by the behavior of thepolymers when heated. Thus, synthetic polymers which characteristicallybecome hard and infusable upon application of heat may be classified asthermosetting polymers, while those synthetic polymers whichcharacteristically soften upon application of heat and which are capableof re-softening are classified as thermoplastic polymers. Exemplarythermoplastic poly-- mers are those prepared by the polymerization ofvinyl compounds such as vinyl acetate, vinyl chloride, vinylchloride/vinyl acetate mixtures, vinyl aldehyde, vinyl alcohol and thelike, styrene, ethylene, cyclopentadiene, acrylics such as methylmethacrylate, fluorocarbons, terephthalic acid esters and the like.Exemplary thermosetting polymers are phenolic resins such as thephenolformaldehyde resins, the resorcinol-formaldehyde resins,urea-formaldehyde resins, melamines, epoxy resins and the like. Anothersynthetic polymer, which until recently has been classified as athermosetting polymer, is polyurethane.

The polyurethane resins possess certain desirable physical properties,such as high tensile strength and excellent solvent and abrasionresistance, which has led to their use in the fabrication of a widevariety of articles. Commonly, the polyurethanes have been prepared bythe reaction of a polyisocyanate such as tolylene diisocyanate, and amultihydroxyl compound such as polyethylene glycol. More broadly,however, polyurethanes may be formed by a variety of methods known inthe art, the most widely known method being the reaction of diorpolyfunctional hydroxyl compounds, for example polyesters or polyethershaving terminal hydroxyl groups, with dior polyfunctional isocyanates.

One of the earlier patents describing such methods is US. Patent No.2,284,896 which describes the reactions of polyfunctional compoundscontaining active hydrogen atoms with polyisocyanates. Such poylurethaneresins are classified as thermosetting resins and as such are only verydifiicultly adaptable to high speed processing techniques such asextrusion. Softening such thermosetting polyurethanes, by the additionof hydrocarbon softening or processing oils or by addition ofconventional "ice ester plasticizers, makes the polymer more easilyprocessable but also results in a product having unsatisfactory physicalproperties. Coatings prepared from such thermosetting polyurethanes havenot proved to be entirely satisfactory, since they must be applied to asubstrate material by such methods as dipping, coating or spraying,these methods being rather slow and producing a bond between thepolyurethane coating and the substrate which has not proved to besufficiently strong for many industrial applications.

It has been only recently that polyurethanes have been developed whichmay be classified as thermoplastic resins. In contrast to thethermosetting polyurethanes described above, the newly developedthermoplastic polyurethanes may be easily extruded, as will be morefully described hereinafter, to form an easily applied and stronglyadherent coating.

As indicated above, it has been the practice to apply thermosettingpolyurethane coatings to articles composed of various types of plasticmaterials by dipping, spraying or painting a solution of an uncuredthermosetting polyurethane onto the plastic article to be protected andthereafter heating the polyurethane in order to cure it. Such techniquesare, obviously, time consuming and, moreover, do not provide asatisfactorily strong bond between the polyurethane coating and thesubstrate material. Due to the poor bonding between the layers in such astructure, each layer of plastic material acts more or lessindependently instead of in cooperation with the other layer or layers.

Accordingly, in view of the difficulties experienced in the prior art inobtaining satisfactory laminated articles comprising a thermosettingpolyurethane, it is an object of this invention to provide novellaminated structures comprising a thermoplastic polyurethane material,said thermoplastic polyurethane being incorporated into such structurein the form of one or more thin layers.

Another object of this invention is to provide novel structurescomprising a vinyl polymer having a thin film of thermoplasticpolyurethane bonded thereto.

A further object of this invention is to provide novel structurescomprising a substrate of thermoplastic vinyl polymer having a thin filmof thermoplastic polyurethane bonded thereto.

A further object of this invention is to provide novel structurescomprised of a homogeneous mixture of a vinyl polymer and athermoplastic polyurethane.

Another object of this invention is to provide a method for applying athin film of thermoplastic polyurethane to a vinyl polymer substrate.

Another object of this invention is to provide a method for forming anarticle comprised of a vinyl polymer and simultaneously applying theretoa thin film of thermoplastic polyurethane.

The above objects, and other objects which will become apparent to thoseskilled in the art, are attained by the present invention wherein,briefly, novel laminated plastic structures are formed by applying athin film of a thermoplastic polyurethane elastomer to a vinyl polymersubstrate or by blending a thermoplastic polyurethane elastomer with asuitable vinyl thermoplastic polymer material to form a mixture andthereafter subjecting the mixture to molding temperatures to obtain ahomogeneous composition and subsequently shaping the homo geneouscomposition, if necessary. A further aspect of this invention comprisesforming structures having a plurality of layers, wherein alternatelayers are composed of a thermoplastic polyurethane resin.

Further aspects of this invention will become apparent from thefollowing detailed description when taken in connection with theaccompanying drawings which illustrate preferred embodiments of theinvention and where- FIGS. 1 and 2 illustrate a 'multilayered, compositetubular structure such as a garden hose or the like. The core orsubstrate is composed of a thermoplastic vinyl polymer such as, forexample, polyvinylchloride of conventional wall thickness, i.e., 0.055inch to 0.125 inch. Bonded thereto is a thin film 14 of polyurethanewhich Was formed during simultaneous extrusion of the core and the film. Due to the unique bond formed between the thermoplastic polyurethaneand the thermoplastic vinyl polymer by the method of this invention, ithas been found that garden hoses produced therefrom have burst strengthswhich show significant improvement over the use of commercial vinylpolymer garden hose. It has been found, for example, that garden hosecomprising a thin thermoplastic polyurethane film of approximately 310mils in thickness has a burst strength on the order of 100 lbs. greaterthan the core alone and significantly greater than commercial vinylgarden hose.

FIGS. 3 and 4 illustrate another embodiment of a laminated tubularstructure which may be prepared in accordance with the method of thisinvention and which may be utilized for gasoline hose and the like. Inthis embodiment, a tubular core 18 of a thermoplastic vinyl polymer isprovided with a thin film of thermoplastic polyurethane, 22 and 26, onthe interior and exterior surfaces thereof. The exterior polyurethanesurface provides excellent wear and abrasion properties and, coupledwith the interior polyurethane film 26 and vinyl polymer core 18,provides a flexible, light-weight hose having exceptionally high burststrength.

A further embodiment of a laminated tubular structure of the inventionis illustrated in FIGS. 5 and 6 wherein a tubular structure composed oftwo layers, 30 and 34, of a thermoplastic vinyl polymer is reinforced bya thin thermoplastic polyurethane film 38 interposed therebetween andbonded thereto.

The method of simultaneously extruding the core 10 and the film 14,illustrated in FIGS. 1 and 2, is shown in FIG. 7. Simultaneous extrusionapparatus 42 permits the film 14 and tubular core 10 to be extruded andfused while each is still in a partially molten condition duringextrusion. A superior high strength bond is thereby attained.

FIG. 8 illustrates a composite tubular structure made in accordance withthis invention and embodying a homogeneous composition prepared from ablended mixture of a thermoplastic vinyl polymer and a thermoplasticpolyurethane elastomer.

FIG. 9 illustrates another extrusion method of the in vention wherein afirst extrusion apparatus 46 extnudes the tubular thermoplastic vinylpolymer core 10 while a subsequent extruding apparatus 50 extrudes athin thermoplastic polyurethane film 14 onto the surface of the core 10,thus effecting a fusion between the film 14 and core 10 by virtue of thehot state of the thermoplastic film as it issues from the extruder.

Another practical application of the present invention is illustrated inFIG. 10 wherein a door threshold is shown, in transverse section, havinga rigid support member adapted to be secured to the threshold by nailingor screwing or by other suitable means and comprised of a thermoplastic,r-igid vinyl substrate and a thin film 68 of a thermoplasticpolyurethane on selected surface areas thereof. A flexible sealingmember 64, which may also be a thermoplastic vinyl polymer, may besimilarly protected with a thin surface of thermoplastic polyurethanefilm and adapted to deformably engage a door, window or the like. Thethin film of polyurethane 68 is extruded or molded onto the thresholdsupport member and the threshold sealing member to withstand the greatabrasive forces which can be expected on such door pieces. Because ofthe high strength of the bond between the thermoplastic polyurethanefilm and the vinyl polymer substrate, adhesive materials are notnecessary.

Another threshold sealing device is illustrated by transverse section inFIG. 11 'wherein there is shown a substrate member 72, a flexiblesealing member 76 removably attached thereto and a thin film ofthermoplastic polyurethane film 80 and 81 bonded to the exposed surfacesthereof.

In accordance with the present invention, composite structures areprepared which comprise one or more layers of thermoplastic vinylpolymer and one or more layers, in the form of thin films, ofthermoplastic polyurethane.

The vinyl polymers which may be used to prepare articles of manufacturein accordance with the present invention are prepared from ethylenicallyunsaturated monomers such as the vinyl halides, e.g. vinyl chloride andvinylidene chloride; olefins such as ethylene and propylene; unsaturatedacid esters such as vinyl acetate, methylmethacrylate and ethylacrylate;or vinyl aromatics such as styrene and the like which are conventionallyprepared by solution, dispersion or emulsion polymerization techniques.When it is intended that a foamed vinyl polymer be used, blowing agentswhich release CO (e.g. NaHCOz), N (e.g. azides), N0 (e.g. nitrosocompounds) and the like may be incorporated therein prior to extrusion.

The thermoplastic polyurethanes which are used to form the compositeplastic articles of the present invention are polyester urethanes which,for example, may be prepared by the reaction of a hydroxyl terminatedpolyester, an aromatic diisocyanate and an alkoxy diol. The ratio ofpolyester and alkoxy diol to aromatic diisocyanate is such that there isessentially no free unreacted diisocyanate, diol or polyester remainingafter the reaction. The thermoplastic polyurethanes may be prepared byreacting, for example, one mole of a hydroxyl terminated polyester withfrom about 1 to 3 moles of an alkoxy diol and from about 2 to 4 moles ofan aromatic diisocyanate. The ratio of reactants is regulated in amanner such that the molar equivalent of aromatic diisocyanate equalsthe combination of the molar equivalents of polyester and alkoxy diolpresent in the reaction mixture.

The polyester is a hydroxyl terminated polyester having a molecularweight between about 500 and 5000 and may be prepared, for example, byesterification of an aliphatic dicarboxylic acid or anhydride thereofwith a glycol. Polyesters may be prepared for example, by esterificationof aliphatic dicarboxylic acids such as adipic, succinic, sebacic or thelike or their anhydrides.

The aliphatic diols which may be utilized in the preparation of thepolyester are aliphatic diols such as 1,4- butanediol, ethylene glycol,trimethylene diol, hexmethylene diol and the like.

Alkoxy diols which may be employed in the preparation of the polyesterurethanes used in the invention may be di(hydroxyalkoxy)-aromaticcompounds such as, for example, 1,4-bis(2-hydroxyethoxy)benzene,1,4-bis(3-hydroxypropoxy) benzene and like. Such compounds are preparedby reacting an alkylene chlorohydrin or alkylene oxide with anappropriate dihydroxy compound such as hydroquinone, resorcinol and thelike.

The aromatic diisocyanates used to prepare the polyester urethanes mayinclude such materials as, for example, dichlorodiphenylmethanediisocyanate, dimethyldiphenylmethane diisocyanate, 4,4'-diphenylmethanediisocyanate and the like.

Suitable thermoplastic polyurethane elastomers which may be used inaccordance with the present invention are the currently availablecommercial products designated by the trademarks Texin (Mobay ChemicalCo.) and Estane (B. F. Goodrich Chemical Co.) As generally disclosed inWalker, Texin Solid Urethane Elastomers, Rubber World, vol. 144, No. 4,July 1961, pp. 76-77 and 84; dAdolf, Urethane Rubbers Growing in Use,Rubher World, vol. 144, No. 4, July 1961, pp. 67-71; Texin Topics, MobayChemical Co.; Data Sheet-Texin 480A, Mobay Chemical Co., March 1962;Technical Information Bulletin 62-E19, Mobay Chemical Co., I an. 23,1961; Canadian Patent No. 640,610 issued May 1, 1962; US. Patent No.2,729,618 (example 12) issued Jan. 3, 1956, Texin may be described as apolyurethane elastomer exhibiting thermoplastic characteristics made byreacting from 20-100 parts by weight of a diisocyanate with 100 parts byweight of a polyester, to said reaction mixture being added across-linking agent such as 1,4-butane diol. Estane is a truethermoplastic elastomer in that it is virtually completely cured and yetretains its thermoplastic nature. It is prepared from4,4-diphenylmethane diisocynanate, adipic acid and 1,4-butanediol. Itsstructure may be represented as follows:

where Z is L Jr.

and R is The number average molecular weight of the elastomer is about36,000. It does not require the use of vulcanizing agents such asperoxides, etc. and is thermoplastic though virtually completely cured.The table, below, summarizes and compares the more important physicalproperties of a typical thermoplastic elastomer of the type describedabove with a conventional plasticized polyvinyl chloride resin.

TABLE Thermo- Property PVC plastic Polyurethane Melt index at- 44p.s.i., 190 C., g./ min"- 0.2 1 440 p.s.i., 190 C., g./10 min 40Density, 23"]4 C., gJcc .1 1. 21 Vieat Softening Point, 67 TensileStrength, p.s.i 4, 560 Brittleness index, 80% pass, C 65 Tearresistance, lb./in 475 705 Grease resistance Flex-crack resistance,total length of s after 500,000 cycles at 23 0., mils 250 121 Abrasionresistance, g. lost/1,000 cycles 0.083 0. 0005 1 Failed in 24 hr. 2 N0failures in 24 hr.

As shown by the figures hereinabove discussed, for example, FIG. 7 whichshows a solid thin film 14 of polyurethane, the thermoplasticpolyurethanes contemplated by the present invention are nonfoamedelastomers. The term nonfoamed is well known in the art and this Wellknown meaning of the term is applicable here.

By virtue of the exceptionally tight fusion resulting from thesimultaneous extrusion of the composite vinyl polymer/ thermoplasticpolyurethane articles made in accordance with the invention, sucharticles exhibit properties which are not merely cumulative in effectbut which are greater than the sum of the properties of the individualresins utilized. It is believed that this effect is achieved because ofthe unique bonding which takes place between the vinyl polymer and thethermoplastic polyurethane which is not attained by prior art methods ofcoating articles with athermosetting polyurethane. The followingexamples will serve to further illustrate preferred embodiments of theinvention.

It is to be understood, however, that the examples are not intended tobe construed as limitation of the scope of the invention, but are merelyillustrative.

Example 1 A thermoplastic vinyl polymer formulation was preparedcomprising polyvinyl chloride, di-isooctyl phthalate as primarypl'asticizer, epoxidized soybean oil as secondary plasticizer andmechanically ground calcium carbonate. The material was then fed to astorage bin for subsequent use in the preparation of tubing which wastested in accordance with the examples set forth below.

At the same time, a linear thermoplastic polyurethane elastomer wasprepared from diphenylmethane-p,p'-diisocyanate, adipic acid andbutanediol-1,4. This material was also transferred to a storage bin forfurther use in the examples set forth below.

Example 2 The polyvinyl chloride resin and the thermoplasticpolyurethane resin described in Example 1 were separately butsimultaneously extruded in accordance with the method illustrated inFIG. 7 to form a tube having a wall thickness of .070 inch and, bondedthereto, a thin, exterior film of thermoplastic polyurethane having athickness of .010 inch. Such tubing is suitable for garden hoseconstruction. Theburst pressure of the garden hose so prepared wastested and the product was found to have a burst strength of 225 p.s.i.

In comparison with the garden hose described above and which wasprepared in accordance with this invention, a garden hose having an .080inch wall but consisting solely of polyvinyl chloride was tested andfound to have a burst strength of only p.s.i.

For further comparison, a commercial vinyl hose consisting of a core ofscrap which was skin-coated with polyvinyl chloride resin was tested andwas found to have a burst strength of p.s.i. The commercial vinyl hosehad a wall thickness varying from .080-.085 inch.

Example 3 The materials described in Example 1 were simultaneouslyextruded to form a garden hose having a wall thickness of .085 inch and,bonded thereto, a thin exterior film having a thickness of .005 inch, ofthermoplastic polyurethane. The garden hose so constructed was found tohave a burst strength of 245 p.s.i.

A second garden hose was prepared which consisted solely of polyvinylchloride and having a wall thickness of .090 inch. This garden hose hada burst strength of 200 p.s.i.

A commercial vinyl garden hose consisting of an inner tubular core ofpolyvinyl chloride scrap and an outer skin of high grade polyvinylchloride. The commercial hose had an overall wall thickness varying from.080- .085 inch. This hose was tested and found to have a burst strengthof 170 p.s.i.

Example 4 Two garden hoses were prepared. One was prepared in accordancewith the method of this invention and consisted of an inner tubular coreof polyvinyl chloride having a wall thickness of .085 inch and a thinouter film of thermoplastic polyurethane having a thickness of .005inch. The second garden hose was prepared from high grade commercialpolyvinyl chloride resin' and had a wall thickness of .090 inch. Varioustubular sections were prepared from each hose formulation at varyingextruder speeds. The hose sections thus prepared were then tested andtheir comparative burst strengths noted. The extruder speeds and theburst strengths obtained from the hoses prepared at each extruder speedare set forth below.

Burst Strength (lbs. per square inch) PVC (.085 inch) Polyurethane PVC(.090 inch) (.005 inch) Speed, FtJMin.:

Example then compared. The results are listed below:

PVC Blend Hardness, Shore A 83 83 Tensile, p.s.i 1,839 2,052 Modulus,100% .l 1, 197 1, 159 Elongation 292 324 Similar results were obtainedwhen hoses were prepared containing blends of from 85-94% polyvinylchloride and correspondingly from -6% thermoplastic polyurethane.

When it is desired to produce articles having a configuration other thantubular, the mixture of vinyl polymer and polyurethane is heated tomolding temperature in order to effect a homogeneous composition and thecomposition is then subjected to conventional plastic article formingprocedures.

It is to be understood that articles may be prepared as described hereinwhere the vinyl polymer substrate is in the form of a foam. In thisaspect of the invention, the selected vinyl polymer base formulation ismixed with a blowing agent, as set forth above, in a ratio of from sixto 100 grams of blowing agent per 100 pounds of polymer formulationprior to extrusion. For best operation of the extruder and for bestcontrol of surface quality, the ratio of blowing agent to vinyl polymerformulation is preferably in the range of about to about 40 grams ofblowing agent per 100 pounds of vinyl polymer formulation.

The blowing agent may be added either in dry or paste form. Thepreferred method is to add the blowing agent to the vinyl polymerformulation as a paste consisting of 50% to 70% blowing agent indioctylphthalate.

In the above examples, the composite laminated articles are preferablyformed by simultaneous extrusion as illustrated in FIG. 7. Thepolyvinylchloride extruder has a diameter of 2 to 2 /2 inches andcomprises four heating zones set at successively higher temperatures ofabout 280 F., 300 F., 320 F. and 340 F. The polyurethane extruder has adiameter of about 1%. inches and traverses two heating zones whereintemperatures are maintained at about 320-340 F. From the extruders, themelts are fed to at least one and preferably to a plurality of dieswhich are heated to the same temperature as the extruder heads. As themelts issue from the extruders, they are united while still hot so as tofuse the layers of polyvinylchloride and polyurethane to each other. Ifthe article being prepared is a hollow structure such as a tube, air isentered through a spider in the die in order to keep the tube fromcollapsing. The article is then transferred to a water bath where thearticle is quenched. The water is then blow olf and the article, if atubular structure, is cut to length. Further details as to the apparatusdiscussed hereinabove and method of forming articles are set forth inapplicants copending application, Ser. No. 314,699 filed Oct. 8, 1963,now US. Patent No. 3,331,900 issued July 18, 1967.

When the article to be prepared is to consist of a foamedpolyvinylchloride substrate, a blowing agent as set forth above ismetered to the extruder in such a manner that the blowing agentdecomposes while issuing from the extruder head. Thus, in order toachieve foaming at the proper time for extrusion, it is essential thatthe blowing agent have a decomposition temperature corresponding to themelt temperature of polyvinylchloride, i.e. 320-330 F.

It is to be understood that the thermoplastic compositions from whicharticles are prepared in accordance with this invention may containconventional compounding agents such as fillers, pigments, dyes,stabilizers, plasticizers and the like.

Further, it is obvious that a great variety of articles may be preparedin accordance with this invention, including furniture tape, furniturewelting, cover base, floor tile, window channels, auto panels,disposable oil containers, mortar boxes, disposable soft drink bottlesand the like.

Obviously many modifications and variations of the invention arepossible in the light of the above teachings. It is therefore to beunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

I claim:

1. A laminated structure comprising a layer of a vinyl polymer bonded toa strongly adherent layer of a nonfoamed thermoplastic polyurethane,said bond being a fusion bond and requiring no additional adhesivematerials.

2. A laminated structure according to claim 1 wherein said layer ofpolyurethane is a thin film thereof.

3. A laminated structure according to claim 2 comprising a plurality oflayers wherein alternate layers comprise said thin film of polyurethane.

4. A laminated structure according to claim 2 wherein said layer ofvinyl polymer is a foamed layer of said polymer.

5. A laminated structure according to claim 2 wherein said layer ofvinyl polymer is of tubular configuration.

6. A laminated structure according to claim 5 wherein a thin film ofthermoplastic polyurethane is bonded to the interior and exteriorsurfaces of said tubular vinyl polymer layer.

7. A process of forming a laminated strongly bonded structure of a vinylpolymer and a strongly adherent thermoplastic polyurethane without theaddition of adhesives comprising extruding a layer of vinyl polymer,forming a thin film of said thermoplastic polyurethane, contacting saidlayer of vinyl polymer with said thin film of thermoplastic polyurethanewhile at their fusion temperature to thereby form a strong fusion bondbetween said film and said layer.

8. A process according to claim 7 wherein said thin film of polyurethaneis formed by extruding it simultaneously with the extrusion of saidlayer of vinyl polymer.

N 0 references cited.

EARL 'M. BERGERT, Primary Examiner.

C. B. COSBY, Assistant Examiner.

